1. Field of the Invention
The present invention relates to the field of load cells, which are transducers for measuring forces or weights, and in particular, to applications where viscous damping of the load cell is called for because fast settling time or filtering out vibrations is necessary.
2. Description of The Prior Art
Load cells have been used with viscous damping devices and are generally of three types: (1) Standard dashpot arrangements in which a piston moves within a cylinder where the piston generally fits the inside of the cylinder with a very small radial gap. In this way, the small radial gap prevents any leakage flow between the piston and cylinder while the piston also contains a controlled narrow passage through which fluid flows from one side of the piston when the latter moves and in which the passage flow provides the viscous damping; (2) Another method is the one disclosed by U.S. Pat. No. 5,232,062 and according to which the gap between a piston and a cylinder is of no importance and hence can be quite wide; (3) The third method uses the shear of the fluid between two parallel and close plates moving in parallel to one another.
In all of the known prior art, the damping device is external to the load cell and is added to a conventional load cell. It is therefore the object of the present invention to disclose an integral arrangement of a damping device inside the body of the load cell, thus forming a dedicated damped load cell.